The Perseids!

The radiant for the Perseids.  Click for a expanded chart you can use to locate the constellation Perseus.  Credit: thenineplanets.org

The radiant for the Perseids. Click for a expanded chart you can use to locate the constellation Perseus. Credit: thenineplanets.org

One of the best meteor showers of the year is about to reach its peak. The Perseids is a shower not to be missed.

Meteor showers, in a nutshell, come from the debris trail of comets. As a comet moves through its orbit, it can shed bits of debris for various reasons from dust size on up. In particular when a comet gets close enough to the sun for it to warm slightly and become “active” and the volatiles and dust are streamed away creating the familiar comet tail from the comet tail. What remains is a rather persistent trail of debris. We see meteor showers when the Earth passes through these debris trails.

Not all debris trails are created equal in the amount of debris they contain as you might expect, nor does the Earth always hit the debris trail fully. Therefore some showers are better than others and sometimes a particular shower can vary from year to year.

A couple more things, meteor showers are generally named for the area they seem to come or radiate from (or near), hence the term “the radiant”.

We should define the terms meteor and meteorites. We get a little sloppy and use the two interchangeably, a meteor makes the streak we can see (aka falling star) and a meteorite is a meteor that makes it to the ground. By the way a meteoroid is the little (or big) chunk of iron or rock orbiting around in space. Don’t worry that much about it though not many will ‘call you out’ on it, I certainly won’t.

So the progression is: A meteoroid hits the atmosphere and creates a bright streak and becomes a meteor, most burn up, those that don’t and survive to the ground is a meteorite.

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